Database Interview Questions and Answers
Question - 41 : - What do you understand by Join?
Answer - 41 : - Join is the process of deriving the relationship between different tables by combining columns from one or more tables having common values in each. When a table joins with itself, it is known as Self Join.
Question - 42 : - What do you understand by Index hunting?
Answer - 42 : - Index hunting is the process of boosting the collection of indexes which helps in improving the query performance as well as the speed of the database.
Question - 43 : - Explain the importance of Database partitioning.
Answer - 43 : -
The importance of Database partitioning are:
- Improves query performance and manageability.
- Simplifies common administration tasks.
- Acts as a key tool for building systems with extremely high availability requirements.
- Allows accessing a large part of a single partition.
Answer - 44 : -
Database partitioning is the process of partitioning tables, indexes into smaller pieces in order to manage and access the data at a finer level.
This process of partitioning reduces the cost of storing a large amount of data as well as enhances the performance and manageability.
Question - 45 : - Define checkpoint.
Answer - 45 : - Checkpoint declares a point before which all the logs are stored permanently in the storage disk and is the inconsistent state. In the case of crashes, the amount of work and time is saved as the system can restart from the checkpoint.
Question - 46 : - Define Phantom deadlock.
Answer - 46 : - Checkpoint declares a point before which all the logs are stored permanently in the storage disk and is the inconsistent state. In the case of crashes, the amount of work and time is saved as the system can restart from the checkpoint.
Question - 47 : - What do you understand by ‘Atomicity’ and ‘Aggregation’?
Answer - 47 : -
Atomicity is the condition where either all the actions of the transaction are performed or none. This means, when there is an incomplete transaction, the database management system itself will undo the effects done by the incomplete transaction.
Aggregation is the concept of expressing the relationship with the collection of entities and their relationships.
Question - 48 : - What do you understand by Fragmentation?
Answer - 48 : - Fragmentation is a feature that controls the logical data units, also known as fragments that are stored at different sites of a distributed database system.
Question - 49 : - What are the disadvantages of a Query?
Answer - 49 : -
Disadvantages of a Query are:
- Indexes are not present.
- Stored procedures are excessively compiled.
- Difficulty in interfacing.
Answer - 50 : -
Clustered index alters the table and re-order the way in which the records are stored in the table. Data retrieval is made faster by using the clustered index.
A Non-clustered index does alter the records that are stored in the table but creates a completely different object within the table.